1. Field of the Invention
The present invention relates to an electric recording system for recording images on a recording medium such as the commercial thermo-sensitive paper.
2. Description of Prior Art
Various methods of recording images on a sheet of a recording medium have been known as follows.
Primary coloring systems wherein a recording medium has a color developing layer (primary coloring) and images are recorded depending upon the energy data applied by various manners.
Secondary coloring systems such as a method of forming latent images on a recording medium and then coloring the images with a developing agent e.g. toner and a method of forming images on a transferring sheet and then, printing the images on a parmanent recording medium.
The primary recording systems include a discharge recording system, an electrolytic recording system and an electric recording system for forming images by electric energy through a recording needle as well as a heat sensitive recording system for forming images by using heat energy given by a heated pen.
The primary coloring systems have advantages that the structure of the recording device is simple and can be easily formed in compact and economical manner because the recording medium itself has the color developing layer. On the contrary, it is disadvantageously necessary to coat the color developing layer on the recording medium and the cost is high and the processing cost is high.
The heat sensitive recording system is considered to be useful as the recording system for a facsimile and a commutor printer because of low cost of the recording paper in comparison with another primary color developing system.
The conventional thermal heads for thermal printers include three types of a thin film type, a thick film type and a semiconductor type which have certain disadvantages.
In order to prevent wearing of the thermal head caused by sliding on the thermo-sensitive paper, the heat transfer for the recording is performed through a wear-resistant layer. In the thin film type and the thick film type of thermal head, an electrode layer and a resistant layer are formed on a ceramic substrate by a metal deposition, etc. whereby the heat response is too slow.
On the other hand, the electrostatic recording electro photography has been proposed as the secondary coloring system.
The latter system has the advantages that when a toner printing system is employed, a regular paper and plastic sheet can be used as the recording medium whereby the processing cost is low and the recording medium can be selected from various ones. On the contrary, the structure of the recording device is complicated whereby the device is not easily miniaturized and is expensive.
As described above, in the conventionl recording systems, the miniaturization and the cost-down of the recording devices cause the cost-up of the processings.